[RFC] Keyrings: How to make them more useful

[James Bottomley]

On Thu, 2025-06-12 at 13:36 +0100, David Howells wrote:
[...]
> Thoughts?

One of the problems I keep tripping over is different special casing
for user keyrings (which are real struct key structures) and system
keyrings which are special values of the pointer in struct key *.

For examples of what this special handling does, just look at things
like bpf_trace.c:bpf_lookup_{user|system}_key

Since the serial allocation code has a hard coded not less than 3
(which looks for all the world like it was designed to mean the two
system keyring id's were never used as user serial numbers) I think we
could simply allow the two system keyring ids to be passed into
lookup_user_key() (which now might be a bit misnamed) and special case
not freeing it in put_key().

Regards,

James